Response retrieval systems such as computer implemented dialogue systems are provided in many situations. For example, telephone help systems, chat bots, customer service, e-banking etc.
Typically dialogue systems are constructed around rigid ontologies, where conversations are modelled as a sequence of actions that constrain slots to certain values.
This method of modelling dialogue presents two main challenges. Firstly, it is difficult to collect data labelled with these explicit semantic representations. Secondly, it constrains the types of dialogue the system can support, resulting in artificial conversations, and breakdowns when the user does not understand what the system can and cannot support.